diff --git a/lib/attr_encrypted.rb b/lib/attr_encrypted.rb
index 3bfa87c9..8e8e3943 100644
--- a/lib/attr_encrypted.rb
+++ b/lib/attr_encrypted.rb
@@ -159,8 +159,11 @@ def attr_encrypted(*attributes)
       end
 
       define_method("#{attribute}=") do |value|
-        send("#{encrypted_attribute_name}=", encrypt(attribute, value))
-        instance_variable_set("@#{attribute}", value)
+        old_value = instance_variable_get("@#{attribute}")
+        if old_value.nil? || old_value != value
+          send("#{encrypted_attribute_name}=", encrypt(attribute, value))
+          instance_variable_set("@#{attribute}", value)
+        end
       end
 
       define_method("#{attribute}?") do
diff --git a/test/attr_encrypted_test.rb b/test/attr_encrypted_test.rb
index 0afbd37c..6b4c5335 100644
--- a/test/attr_encrypted_test.rb
+++ b/test/attr_encrypted_test.rb
@@ -463,4 +463,13 @@ def test_should_not_by_default_generate_iv_when_attribute_is_empty
     user.with_true_if = nil
     assert_nil user.encrypted_with_true_if_iv
   end
+
+  def test_should_not_generate_iv_if_same_value
+    user = User.new
+    assert_nil user.encrypted_email_iv
+    user.email = 'thing@thing.com'
+    refute_nil(old_value = user.encrypted_email_iv)
+    user.email = 'thing@thing.com'
+    assert_equal old_value, user.encrypted_email_iv
+  end
 end